The title compound, [BiI2(C6H18N3OP)(4)](I-5), contains the pseudo-oct
ahedral Bi-III cation [BiI2{OP(NMe2)(3)}(4)](+), which has crystallogr
aphic (4) over bar symmetry, and trans iodide ligands. The central I a
tom of the disordered [I-5](-) anion is also situated on a site of (4)
over bar symmetry and the atoms of this anion form an infinite three-
dimensional network, resulting in a 'cage'-type structure. The cations
are situated within the 'cage' cavities.